This invention relates to a method of manufacturing a magnetic head used for the playback of a magnetic tape such as a magnetic tape recorded with a vertical magnetization recording system, and also to a magnetic head manufactured by the same method.
In a vertical magnetization recording system, in which a magnetic thin film is magnetized in a direction normal to the surface thereof, a magnetic thin film tape having magnetic anisotropy in a direction normal to its surface is used as a recording medium. In this recording system, magnetization of the recording medium in the direction normal to its surface is effected without self-demagnetization by a demagnetizing field. Thus, this system permits recording of information at a very high density compared to the case of the conventional horizontal or surface direction recording system. In this vertical recording system, the method of recording information on a magnetic tape is considerably different from that in the horizontal or surface direction recording system. For this reason, a head having a novel construction has been developed as the recording head for the vertical recording system. Hitherto, however, an ordinary ring-like head has been used as the reproducing head.
With the prior ring-like reproducing head, however, the reduction of or narrowing of the gap width is restricted by the reproduction efficiency. With the prior-art ring-like head, therefore, difficulties are involved in the reproduction of information of very short wavelengths. Also, even if one tries to reduce the gap width while ignoring the reproduction efficiency, it is impossible to make the gap width extremely narrow due to restrictions imposed on processing techniques. When processing a very narrow gap section, the magnetic permeability of the magnetic material of the head in a high frequency region is reduced by this processing. This means that the gap width is increased in practice. In other words, even if a gap of a mechanically narrow size is merely produced, the effective gap width is not exactly as narrow as that size. Further, when the gap width is made narrow, the surface roughness of the gap section becomes noticeable. This surface roughness is a factor in increasing the effective gap width. The lower limit of the effective gap width that is obtainable with the prior-art processing techniques is about 1 .mu.m.
With the vertical magnetization recording system, it is possible to obtain a very high information recording density. With the prior-art ring-like reproducing head, however, it is hard to obtain an effective gap width smaller than 1 .mu.m due to the afore-mentioned reasons, so that the recorded information with very high density cannot be reproduced. In other words, the frequency range of reproduction is narrower than that of recording. If it is intended to extend the frequency range of reproduction, very difficult processing techniques are required with the prior-art ring-like head.